The present invention relates to a copy paper supply timing control system in a copying machine of the optical system reciprocating type.
Generally, there are two types of timing control systems for controlling the copy paper supply timing. The first type includes a slit plate secured to a shaft of a photosensitive drum. The slit plate has a plurality of slits formed at predetermined positions. Each slit provides a control signal for activating respective elements in the copying machine at desired timings. In this type, the installation of the slit plate requires high accuracy. Moreover, the first type control system is not applicable to a copying machine having an endless photosensitive drum.
The second type includes a slit plate which has slits periodically formed with a predetermined interval. The second type further includes a detection switch for detecting the start point of the reciprocating optical system. A control signal is developed when a preselected number of slits are counted after generation of a detection signal from the detection switch, the control signal being applied to a drive system for activating the elements in the copying machine. This type of the conventional system can not avoid the error up to a magnitude corresponding to the period of the slits. If the error should be reduced, the slit interval must be reduced. This will complicate the slit detection system. Furthermore, even when fine slits are formed, there still exists the error determined by the interval of the slits.
Accordingly, an object of the present invention is to provide a timing control system in a copying machine of the optical system reciprocating type.
Another object of the present invention is to accurately control the copy paper supply timing in a copying machine.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention relates to an improvement over the above-mentioned second type. To achieve the above objects, pursuant to an embodiment of the present invention, a slit plate is secured to a shaft of the photosensitive drum. The slit plate has periodical slits with a predetermined distance therebetween. The copy paper supply timing is controlled so that the copy paper supply is initiated when a preselected time (T) has passed after a predetermined number (N) of slits have been counted from the development of a detection signal derived from an optical system start detection sensor. The preselected time (T), which is selected shorter than a period t' of the slit output, functions to adjust for accurate timing for conducting the copy paper supply.
In a preferred mode, a control circuit is provided which compensates the displacement of the timing of the occurrence of the first slit pulse. The control circuit includes a timer for counting a time period (t) from the development of the detection signal from the optical system start detection sensor to the occurrence of the first slit pulse. When the time period (t) is shorter than or equal to the preselected time (T), the copy paper supply is initiated when (T-t) seconds have passed after the predetermined number (N) of slits have been counted. When the time period (t) is longer than the preselected time (T), the copy paper supply is initiated when (T+t'-t) seconds have passed after the (N-1) slits have been counted, wherein t' is the period of the slit pulses.